Method and device for adaptably controlling bandwidth of channel

ABSTRACT

Disclosed are a base station and mobile station to adaptively control a bandwidth of a channel. The base station includes a state information recognition unit to recognize neighboring-state information related with a traffic load of at least one neighboring network adjacent to a target network, a control state information transmitting unit to transmit control state information related with the controlled bandwidth of the target channel to mobile stations of the target network, and a bandwidth control unit to control a bandwidth of a target channel used in the target network according to a bandwidth of a channel used in the neighboring network based on the neighboring-state information.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2008-0009217, filed on Jan. 29, 2008, in the Korean IntellectualProperty Office, the entire disclosure of which is incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the present invention relates to a method and device toadaptably control a bandwidth of a channel, and more particularly, to amethod and device to adaptably control a bandwidth of a channel whichadaptably controls a channel bandwidth, and transmits informationrelated with the controlled channel bandwidth to mobile stations.

2. Description of the Related Art

In general, a communication system including a cognitive radiocommunication system may divide an available frequency band into a fixedsize, and use the divided frequency band.

For example, it is assumed that A and B networks are present and theavailable bandwidth is 60 MHz. In this instance, a bandwidth of achannel used in each of A and B networks may be generally fixed as 20MHz, respectively, and mobile stations and base stations included in Aand B networks may perform a communication using the fixed bandwidth ofthe channel, respectively.

However, a traffic load of each of A and B networks may be changed dueto mobility of the mobile stations and change in provided services.Specifically, a capacity required in each of A and B networks may bechanged in real time. Accordingly, when A and B networks communicateusing the fixed bandwidth of the channel, respectively, optimum capacityutilization may not be realized.

For example, when a traffic load of B network is about two times higherthan that of A network, using the fixed bandwidth of the channel by Aand B networks may be inefficient.

Therefore, there arises a need for a technique to maximize frequencyefficiency in consideration of a traffic load of a network, acommunication environment, an available frequency band, and the like.

SUMMARY OF THE INVENTION

An aspect of the present invention provides a base station whichadaptably controls a bandwidth in consideration of communicationenvironments of a neighboring network and a target network, and sharesinformation related with the controlled bandwidth with mobile stations,thereby improving frequency efficiency and a transmission rate.

According to an aspect of the present invention, a base station includesa state information recognition unit to recognize neighboring-stateinformation related with a traffic load of at least one neighboringnetwork adjacent to a target network, a control state informationtransmitting unit to transmit control state information related with thecontrolled bandwidth of the target channel to mobile stations of thetarget network, and a bandwidth control unit to control a bandwidth of atarget channel used in the target network according to a bandwidth of achannel used in the neighboring network based on the neighboring-stateinformation.

According to an aspect of the present invention, a mobile stationincludes a control state information reception unit to receive, from abase station of a target network, control state information related witha controlled bandwidth of a target channel, the base station controllingthe bandwidth of the target channel based on a traffic load of at leastone neighboring network adjacent to the target network and a bandwidthof a channel of the neighboring network, and a frequency band settingunit to set a communication frequency band corresponding to thebandwidth of the target channel based on the control state information.

According to an aspect of the present invention, a device to control abandwidth of a channel includes a traffic load recognition unit torecognize a traffic load of a first network and a traffic load of asecond network adjacent to the first network, a bandwidth determinationunit to determine a bandwidth of a first channel used in the firstnetwork and a bandwidth of a second channel used in the second networkbased on a ratio of the traffic load of the first network to the trafficload of the second network, and an information transmitting unit totransmit information related with the determined bandwidths of the firstand second channels to the first network and the second network,respectively.

According to an aspect of the present invention, a method to operate abase station includes recognizing neighboring-state information relatedwith a traffic load of at least one neighboring network adjacent to atarget network, controlling a bandwidth of a target channel used in thetarget network according to a bandwidth of a channel used in theneighboring network based on the neighboring-state information, andtransmitting control state information related with the controlledbandwidth of the target channel to mobile stations of the targetnetwork.

According to an aspect of the present invention, a method to operate amobile station includes receiving, from a base station of a targetnetwork, control state information related with a bandwidth of acontrolled target channel, the base station controlling the bandwidth ofthe target channel according to a traffic load of at least oneneighboring network adjacent to the target network and a bandwidth of achannel used in the neighboring network, setting a communicationfrequency band corresponding to the bandwidth of the target channelbased on the control state information, and feeding-back informationrelated with the set communication frequency band to the base station.Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following detaileddescription of the embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 illustrates a first network and a second network used to describean embodiment of the present invention;

FIG. 2 is a block diagram illustrating a base station according to anembodiment of the present invention;

FIG. 3 illustrates control state information included in a beacon frameaccording to an embodiment of the present invention;

FIG. 4 is a block diagram illustrating a mobile station according to anembodiment of the present invention;

FIG. 5 is an operation flowchart illustrating an operation method of abase station according to an embodiment of the present invention; and

FIG. 6 is an operation flowchart illustrating an operation method of amobile station according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below to explain the presentinvention by referring to the figures.

FIG. 1 illustrates a first network and a second network used to describean embodiment of the present invention.

Referring to FIG. 1, the first network includes a first Mobile Station(MS 1), a second Mobile Station (MS 2), and a first Access Point (AP 1),and the second network includes a third Mobile Station (MS 3), a fourthMobile Station (MS 4), a fifth Mobile Station (MS 5), a sixth MobileStation (MS 6), and a second Access Point (AP 2).

Also, cell coverage 110 of AP 1 and cell coverage 120 of AP2 is shown inFIG. 1, and the first and second networks may use A and B channels,respectively.

In this instance, when each of the mobile stations MS 1, MS 2, MS 3, MS4, MS 5, and MS 6 requires services having an identical capacity, atraffic load generated from each of the mobile stations may beidentical. As illustrated in FIG. 1, it can be seen that two mobilestations MS 1 and MS 2 are included in the first network, and fourmobile stations MS 3, MS 4, MS 5, and MS 6 are included in the secondnetwork. When bandwidths of A and B channels used by the first andsecond networks are identical to each other, the required datatransmission rate may be difficult to be obtained, and the frequencyefficiency may be reduced.

For example, in the case where a wholly available frequency bandwidth is60 MHz, and each of bandwidths of A and B channels is 20 MHz, thetraffic load of the second network is greater than that of the firstnetwork. As a result, qualities of services with which the mobilestations MS 3, MS 4, MS 5, and MS 6 included in the second network areprovided may be deteriorated in comparison with those of services withwhich the mobile stations MS 1 and MS 2 included in the first networkare provided. In addition, a total bandwidth used in the first andsecond networks is 40 MHz, and thus deteriorating the frequency useefficiency due to the unused 20 MHz.

Thus, when the bandwidth is adaptively adjusted according to the trafficload generated from respective networks, the frequency use efficiencymay increase, and services having a desired quality may be provided.

FIG. 2 is a block diagram illustrating a base station according to anembodiment of the present invention.

Referring to FIG. 2, the base station according to the presentembodiment includes a state information recognition unit 210, afrequency band recognition unit 220, a bandwidth control unit 230, and acontrol state information transmitting unit 240.

Hereinafter, it will be described on the assumption that the basestation according to the present embodiment is installed in a targetnetwork. However, a device to control a bandwidth of a channel accordingto the present embodiment may be installed separately from the basestation, and thus adjusting the channel bandwidth used in the first andsecond networks, respectively.

The state information recognition unit 210 may recognizeneighboring-state information related with a traffic load of at leastone neighboring network adjacent to the target network. In thisinstance, the neighboring-state information may further includeinformation related with a number of mobile stations of the neighboringnetwork as well as the traffic load of the neighboring network.

Accordingly, the base station may recognize a communication environmentof the neighboring network such as the traffic load of the neighboringnetwork, the number of mobile stations of the neighboring network, andthe like. In particular, the base station may compare the traffic loadof the target network and the traffic load of the neighboring networkbased on the neighboring-state information, thereby recognizing whichnetwork requires a greater radio resource.

Also, the frequency band recognition unit 220 may recognize a frequencyband capable of being used by the target network. In particular, thefrequency band recognition unit 220 may be unused in another networkusing a cognitive radio technique, or recognize an available frequencyband to minimize the effect of the target network on another network.

Also, the bandwidth control unit 230 may control a bandwidth of thetarget channel used in the target network according to a bandwidth ofthe channel used in the neighboring network based on theneighboring-state information. In particular, the bandwidth control unit230 may control the bandwidth of the target channel based on a ratio ofthe traffic load of the target network to the traffic load of theneighboring network.

For example, when the traffic load of the neighboring network is greaterthan that of the target network, the bandwidth control unit 230 maycontrol such that the bandwidth of the target channel is less than thatof the channel used in the neighboring network. In this instance, thebandwidth of the channel used in the neighboring network is increasingwhile the bandwidth of the target channel is decreasing, and thereforethe neighboring network can appropriately cope with the traffic load.

Also, the control state information transmitting unit 240 may transmitinformation related with the controlled bandwidth of the target channelto the mobile stations of the target network. In this instance, thecontrol state information may include information related with a centerfrequency, noise level, and busy ratio of the target channel.

In particular, the control state information transmitting unit 240 maytransmit the control state information to the mobile stations includedin the target network using a beacon frame.

When the bandwidth of the target channel is adaptively controlled, thecenter frequency, noise level, and busy ratio of the target channel maybe changed. In this instance, the control state information transmittingunit 240 may transmit the center frequency, noise level, and busy ratioof the target channel, which are changed by controlling the bandwidth ofthe target channel, to the mobile stations using the beacon frame.

FIG. 3 illustrates control state information included in a beacon frameaccording to an embodiment of the present invention.

Referring to FIG. 3, a frame body 310 is included in a data frame ofdata transmitted from the base station. A beacon frame 320 may beincluded in the frame body 310, and a control state information 330 maybe included in a beacon frame 320 and thereby the included control stateinformation may be transmitted to the mobile stations.

The control state information 330 may include information 340 relatedwith an Identification (ID), center frequency, bandwidth, noise level,and traffic load of the target channel as shown in FIG. 3, when thefrequency band of the target channel is controlled. In this instance,mobile stations of the target network may acquire the informationrelated with the ID, center frequency, bandwidth, noise level, andtraffic load of the target channel based on the control stateinformation 330 included in the beacon frame 320.

In this instance, the mobile stations of the target network may set acommunication frequency band corresponding to the controlled bandwidthof the target channel based on a frequency band capable of being used bythe mobile stations and characteristics of a Radio Frequency (RF) modulebased on the control state information 330.

In addition, the mobile stations of the target network may reportinformation related with the set communication frequency band to thebase station, and the base station may recognize a communicationfrequency band of the mobile stations of the target network based on theinformation reported by the mobile station. Then, the base station mayperform a downlink communication based on the communication frequencybandwidth of the mobile stations of the target network at a later time.

FIG. 4 is a block diagram illustrating a mobile station according to anembodiment of the present invention.

Referring to FIG. 4, the mobile station according to the presentembodiment includes a control state information reception unit 410, afrequency band setting unit 420, and a result report unit 430.

A base station may control a bandwidth of a target channel based on atraffic load of at least one neighboring network adjacent to a targetnetwork and a bandwidth of a channel used in the target network. Also,the base station may transmit, to the mobile stations, control stateinformation, that is, information related with the controlled bandwidthof the target channel.

In this instance, the control state information reception unit 410 mayreceive, from the base station of the target network, the control stateinformation related with the controlled bandwidth of the target channel.Here, the control state information may include information related witha center frequency, bandwidth, noise level, and busy ratio of the targetchannel, as described above.

Also, the frequency band setting unit 420 may set a communicationfrequency band corresponding to the bandwidth of the target channelbased on the received control state information. Specifically, since thecontrol state information may include information related with thecontrolled bandwidth of the target channel, the frequency band settingunit 420 may set a communication frequency band corresponding to thecontrolled bandwidth of the target channel based on characteristics ofan RF module installed in the mobile station, and a frequency bandcapable of being used by the mobile station.

Also, the result report unit 430 may feed back an operation result ofthe frequency band setting unit 420 to the base station. For example,when the frequency band setting unit 420 changes the communicationfrequency band from an A band to a B band, the result report unit 430may feed back information related with the change in the communicationfrequency band to the base station. In this instance, the base stationmay perform a downlink communication based on the fed back informationat a later time.

FIG. 5 is an operation flowchart illustrating an operation method of abase station according to an embodiment of the present invention.

Referring to FIG. 5, in the operation method of the base stationaccording to the present embodiment, the base station may recognize anavailable frequency band using the cognitive radio technique inoperation S510.

Next, in operation 520, the base station may recognize neighboring-stateinformation related with a traffic load of at least one neighboringnetwork adjacent to a target network.

In operation S530, the base station may control a bandwidth of a targetchannel used in the target network within a range of the recognizedavailable frequency band according to a bandwidth of a channel used inthe neighboring network based on the neighboring-state information.

In this instance, operation S530 to control the bandwidth of the targetchannel may be an operation to control the bandwidth of the targetchannel based on a ratio of a traffic load of the target network to atraffic load of the neighboring network.

In operation S540, the base station may transmit control stateinformation related with the controlled bandwidth of the target channelto the mobile stations included in the target network.

In this instance, the control state information may further includeinformation related with at least one of a center frequency, noiselevel, and busy ratio of the target channel.

FIG. 6 is an operation flowchart illustrating an operation method of amobile station according to an embodiment of the present invention.

Referring to FIG. 6, in the operation method of the mobile stationaccording to the present embodiment, the mobile station may receive,from a base station of a target network, control state informationrelated with a controlled bandwidth of a target channel in operationS620. In this instance, the base station may control the bandwidth ofthe target channel based on a traffic load of at least one neighboringnetwork adjacent to the target network and a bandwidth of a channel usedin the neighboring network, and transmit the control state informationto the mobile station.

In this instance, operation S610 may be an operation to receive thecontrol state information using a beacon frame.

In operation S620, the mobile station may set a communication frequencyband corresponding to the bandwidth of the target channel.

In operation S630, the mobile station may determine whether thecommunication frequency band is changed.

When the communication frequency band is changed, the mobile station mayreport information on the change in the communication frequency band tothe base station in operation S640. Conversely, when the communicationfrequency band is not changed, the mobile station may again performoperation S610.

Descriptions of FIGS. 5 and 6 corresponding to descriptions given withrespect to FIGS. 1 to 4 are herein omitted.

The above-described embodiments of the present invention may be recordedin computer-readable media including program instructions to implementvarious operations embodied by a computer. The media may also include,alone or in combination with the program instructions, data files, datastructures, and the like. The media and program instructions may bethose specially designed and constructed for the purposes ofaccomplishing aspects of the present invention, or they may be of thekind well-known and available to those having skill in the computersoftware arts. Examples of computer-readable media include magneticmedia such as hard disks, floppy disks, and magnetic tape; optical mediasuch as CD ROM disks and DVD; magneto-optical media such as opticaldisks; and hardware devices that are specially configured to store andperform program instructions, such as read-only memory (ROM), randomaccess memory (RAM), flash memory, and the like. Examples of programinstructions include both machine code, such as produced by a compiler,and files containing higher level code that may be executed by thecomputer using an interpreter. The described hardware devices may beconfigured to act as one or more software modules in order to performthe operations of the above-described embodiments of the presentinvention.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made to these exemplary embodiments without departingfrom the principles and spirit of the invention, the scope of which isdefined by the claims and their equivalents.

1. A base station comprising: a state information recognition unit torecognize neighboring-state information related with a traffic load ofat least one neighboring network adjacent to a target network; and abandwidth control unit to control a bandwidth of a target channel usedin the target network according to a bandwidth of a channel used in theneighboring network based on the neighboring-state information.
 2. Thebase station of claim 1, further comprising: a control state informationtransmitting unit to transmit control state information related with thecontrolled bandwidth of the target channel to mobile stations of thetarget network.
 3. The base station of claim 2, wherein the controlstate information further includes information related with at least oneof a center frequency, noise level, and busy ratio of the targetchannel.
 4. The base station of claim 2, wherein the control stateinformation transmitting unit transmits the control state informationusing a beacon frame.
 5. The base station of claim 1, wherein thebandwidth control unit controls the bandwidth of the target channelbased on a ratio of a traffic load of the target network to a trafficload of the neighboring network.
 6. The base station of claim 1, whereinthe state information recognition unit recognizes the neighboring-stateinformation related with a number of mobile stations of the neighboringnetwork, and the bandwidth control unit controls the bandwidth of thetarget channel based on the number of mobile stations of the neighboringnetwork.
 7. The base station of claim 1, further comprising: a frequencyband recognition unit to recognize an available frequency band by thetarget network using a cognitive radio technique, wherein the bandwidthcontrol unit controls the bandwidth of the target channel within a rangeof the available frequency band.
 8. A mobile station comprising: acontrol state information reception unit to receive, from a base stationof a target network, control state information related with a controlledbandwidth of a target channel, the base station controlling thebandwidth of the target channel based on a traffic load of at least oneneighboring network adjacent to the target network and a bandwidth of achannel of the neighboring network; and a frequency band setting unit toset a communication frequency band corresponding to the bandwidth of thetarget channel based on the control state information.
 9. The mobilestation of claim 8, wherein the control state information furtherincludes information related with at least one of a center frequency,noise level, and busy ratio of the target channel.
 10. The mobilestation of claim 8, wherein the control state information reception unitreceives the control state information using a beacon frame.
 11. Themobile station of claim 8, further comprising: a result report unit tofeed back an operation result of the frequency band setting unit to thebase station.
 12. A device to control a bandwidth of a channel, thedevice comprising: a traffic load recognition unit to recognize atraffic load of a first network and a traffic load of a second networkadjacent to the first network; a bandwidth determination unit todetermine a bandwidth of a first channel used in the first network and abandwidth of a second channel used in the second network based on aratio of the traffic load of the first network to the traffic load ofthe second network; and an information transmitting unit to transmitinformation related with the determined bandwidths of the first andsecond channels to the first network and the second network,respectively.
 13. The device of claim 12, wherein the bandwidthdetermination unit determines the bandwidths of the first and secondchannels further based on a number of mobile stations of the firstnetwork, and a number of mobile stations of the second network.
 14. Amethod to operate a base station, the method comprising: recognizingneighboring-state information related with a traffic load of at leastone neighboring network adjacent to a target network; controlling abandwidth of a target channel used in the target network according to abandwidth of a channel used in the neighboring network based on theneighboring-state information; and transmitting control stateinformation related with the controlled bandwidth of the target channelto mobile stations of the target network.
 15. The method of claim 14,wherein the control state information further includes informationrelated with at least one of a center frequency, noise level, and busyratio of the target channel.
 16. The method of claim 14, the controllingcontrols the bandwidth of the target channel according to a ratio of atraffic load of the target network to a traffic load of the neighboringnetwork.
 17. A method to operate a mobile station, the methodcomprising: receiving, from a base station of a target network, controlstate information related with a bandwidth of a controlled targetchannel, the base station controlling the bandwidth of the targetchannel according to a traffic load of at least one neighboring networkadjacent to the target network and a bandwidth of a channel used in theneighboring network; setting a communication frequency bandcorresponding to the bandwidth of the target channel based on thecontrol state information; and feeding-back information related with theset communication frequency band to the base station.
 18. The method ofclaim 17, wherein the receiving receives the control state informationusing a beacon frame.
 19. A computer-readable recording medium storing aprogram for implementing the method of claim 14.